Circular vertical hall magnetic field sensing element and method with a plurality of continuous output signals

ABSTRACT

A circular vertical Hall (CVH) sensing element and an associated method provide a plurality of output signals from a respective plurality of vertical Hall elements in the CVH sensing element at the same time.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and claims priority to U.S. patentapplication Ser. No. 13/035,243 filed on Feb. 25, 2011, whichapplication is incorporated herein by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable.

FIELD OF THE INVENTION

This invention relates generally to magnetic field sensors, moreparticularly, to a circular vertical Hall (CVH) sensing element forwhich output signals are generated by a plurality of vertical Hallelements at the same time.

BACKGROUND OF THE INVENTION

As is known, sensing elements are used in a variety of applications tosense characteristics of an environment. Sensing elements include, butare not limited to, pressure sensing elements, temperature sensingelements, light sensing elements, acoustic sensing elements, andmagnetic field sensing elements.

Magnetic field sensing elements can be used in a variety ofapplications. In one application, a magnetic field sensor can be used todetect a direction of a magnetic field. In another application, amagnetic field sensing element can be used to sense an electricalcurrent. One type of current sensor uses a Hall effect magnetic fieldsensing element in proximity to a current-carrying conductor.

Planar Hall elements and vertical Hall elements are known types ofmagnetic field sensing elements that can be used in magnetic fieldsensors. A planar Hall element tends to be responsive to magnetic fieldperpendicular to a surface of a substrate on which the planar Hallelement is formed. A vertical Hall element tends to be responsive tomagnetic field parallel to a surface of a substrate on which thevertical Hall element is formed.

Other types of magnetic field sensing elements are known. For example, aso-called “circular vertical Hall” (CVH) sensing element, which includesa plurality of vertical magnetic field sensing elements, is known anddescribed in PCT Patent Application No. PCT/EP2008056517, entitled“Magnetic Field Sensor for Measuring Direction of a Magnetic Field in aPlane,” filed May 28, 2008, and published in the English language as PCTPublication No. WO 2008/145662, which application and publicationthereof are incorporated by reference herein in their entirety. The CVHsensing element is a circular arrangement of vertical Hall elementsarranged over a common circular implant region in a substrate. The CVHsensing element can be used to sense a direction (and optionally astrength) of a magnetic field in a plane of the substrate.

Output signals from the vertical Hall elements of a CVH sensing elementare typically generated sequentially, resulting in a substantial timenecessary to generate all of the output signals from the CVH sensingelement.

Various parameters characterize the performance of sensing elements (andsensors that use magnetic field sensing elements) in general, andmagnetic field sensing elements (and sensors) in particular. Taking amagnetic field sensing element as an example, these parameters includesensitivity, which is a change in an output signal of a magnetic fieldsensing element in response to a change of magnetic field experienced bythe magnetic sensing element, and linearity, which is a degree to whichthe output signal of the magnetic field sensing element varies in directproportion to the magnetic field. These parameters also include anoffset, which is characterized by an output signal from the magneticfield sensing element not representative of a zero magnetic field whenthe magnetic field sensing element experiences a zero magnetic field.Other types sensing elements can also have an offset of a respectiveoutput signal that is not representative of a zero sensed characteristicwhen the sensing element experiences the zero sensed characteristic.

It would be desirable to provide circuits that can process sensor outputsignals from a plurality of sensors to provide a processed output signalhaving improved characteristics, including, but not limited to, animproved offset.

It would also be desirable to provide a CVH sensing element arrangementfor which the output signals from the CVH sensing element are generatedmore quickly.

SUMMARY OF THE INVENTION

The present invention provides a circular vertical Hall (CVH) sensingelement and method that can generate a plurality of output signals fromthe CVH sensing element at the same time. A faster CVH sensing elementresults.

In accordance with one aspect of the present invention, a method ofoperating a circular vertical Hall (CVH) sensing element having aplurality of vertical Hall element contacts disposed in a circle over acommon implant region in a substrate, the method includes selecting aplurality of groups of vertical Hall element contacts from among theplurality of vertical Hall element contacts. Each group isrepresentative of a respective one of a plurality of vertical Hallelements. The selecting comprises selecting a first group of verticalHall element contacts representative of a first vertical Hall element,and selecting a second group of vertical Hall element contactsrepresentative of a second vertical Hall element. The method furtherincludes driving at the same time the first and the second vertical Hallelements to provide at the same time a first vertical Hall elementoutput signal between two of the vertical Hall element contacts of thefirst group and a second vertical Hall element output signal between twoof the vertical Hall element contacts of the second group. The first andthe second vertical Hall element output signals are not representativeof opposite magnetic field directions relative to each other.

In accordance with another aspect of the present invention, a method ofoperating a circular vertical Hall (CVH) sensing element having aplurality of vertical Hall element contacts disposed in a circle over acommon implant region in a substrate, the method includes selecting aplurality of groups of vertical Hall element contacts from among theplurality of vertical Hall element contacts. Each group isrepresentative of a respective one of a plurality of vertical Hallelements. The selecting comprises selecting a first group of verticalHall element contacts representative of a first vertical Hall element,and selecting a second group of vertical Hall element contactsrepresentative of a second vertical Hall element. The method furtherincludes driving at the same time the first and the second vertical Hallelements to provide at the same time a first vertical Hall elementoutput signal between two of the vertical Hall element contacts of thefirst group and a second vertical Hall element output signal between twoof the vertical Hall element contacts of the second group. The selectingfurther includes selecting a third group of vertical Hall elementcontacts representative of a third vertical Hall element from among theplurality of vertical Hall element contacts. The driving furtherincludes driving at the same time the third vertical Hall element toprovide at the same time a third vertical Hall element output signalbetween two of the vertical Hall element contacts of the third group.

In accordance with another aspect of the present invention, a method ofoperating a circular vertical Hall (CVH) sensing element having aplurality of vertical Hall element contacts disposed in a circle over acommon implant region in a substrate, the method includes selecting aplurality of groups of vertical Hall element contacts from among theplurality of vertical Hall element contacts. Each group isrepresentative of a respective one of a plurality of vertical Hallelements. The selecting comprises selecting a first group of verticalHall element contacts representative of a first vertical Hall element,and selecting a second group of vertical Hall element contactsrepresentative of a second vertical Hall element. The method furtherincludes driving at the same time the first and the second vertical Hallelements to provide at the same time a first vertical Hall elementoutput signal between two of the vertical Hall element contacts of thefirst group and a second vertical Hall element output signal between twoof the vertical Hall element contacts of the second group. The first andthe second groups of vertical Hall element contacts share at least onevertical Hall element contact with each other.

In accordance with another aspect of the present invention, a circularvertical Hall (CVH) sensing element circuit includes a substrate, acommon circular implant region in a surface of the substrate, and aplurality of vertical Hall element contacts disposed in a circle overthe common implant region and upon the surface. Each group isrepresentative of a respective one of a plurality of vertical Hallelements, a first group representative of a first vertical Hall element,and a second group representative of a second vertical Hall element. Thecircular vertical Hall (CVH) sensing element circuit further includesrespective first and second drive signal generators disposed upon thesubstrate and configured to drive at the same time the first and thesecond vertical Hall elements to provide at the same time a firstvertical Hall element output signal between two of the vertical Hallelement contacts of the first group and a second vertical Hall elementoutput signal between two of the vertical Hall element contacts of thesecond group. The first and the second vertical Hall element outputsignals are not representative of opposite magnetic field directionsrelative to each other.

In accordance with another aspect of the present invention, a circularvertical Hall (CVH) sensing element circuit includes a substrate, acommon circular implant region in a surface of the substrate, and aplurality of vertical Hall element contacts disposed in a circle overthe common implant region and upon the surface. Each group isrepresentative of a respective one of a plurality of vertical Hallelements, a first group representative of a first vertical Hall element,and a second group representative of a second vertical Hall element. Thecircular vertical Hall (CVH) sensing element circuit further includesrespective first and second drive signal generators disposed upon thesubstrate and configured to drive at the same time the first and thesecond vertical Hall elements to provide at the same time a firstvertical Hall element output signal between two of the vertical Hallelement contacts of the first group and a second vertical Hall elementoutput signal between two of the vertical Hall element contacts of thesecond group. A third group selected from the plurality of vertical Hallelement contacts is representative of a third vertical Hall element. Thecircular vertical Hall (CVH) sensing element circuit further includes arespective third drive signal generator disposed upon the substrate andconfigured to drive at the same time the third vertical Hall element toprovide at the same time a third vertical Hall element output signalbetween two of the vertical Hall element contacts of the third group.

In accordance with another aspect of the present invention, a circularvertical Hall (CVH) sensing element circuit includes a substrate, acommon circular implant region in a surface of the substrate, and aplurality of vertical Hall element contacts disposed in a circle overthe common implant region and upon the surface. Each group isrepresentative of a respective one of a plurality of vertical Hallelements, a first group representative of a first vertical Hall element,and a second group representative of a second vertical Hall element. Thecircular vertical Hall (CVH) sensing element circuit further includesrespective first and second drive signal generators disposed upon thesubstrate and configured to drive at the same time the first and thesecond vertical Hall elements to provide at the same time a firstvertical Hall element output signal between two of the vertical Hallelement contacts of the first group and a second vertical Hall elementoutput signal between two of the vertical Hall element contacts of thesecond group. The first and the second groups of vertical Hall elementcontacts share at least one vertical Hall element contact with eachother.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features of the invention, as well as the invention itselfmay be more fully understood from the following detailed description ofthe drawings, in which:

FIG. 1 is a pictorial showing a circular vertical Hall (CVH) sensingelement having a plurality of vertical Hall elements arranged in acircle over a common implant region and a two pole magnet disposed closeto the CVH sensing element;

FIG. 1A is a pictorial showing a plurality of sensing elements (oralternatively, sensors), for example, Hall elements, planar or vertical;

FIG. 2 is a graph showing an output signal as may be generated by theCVH sensing element of FIG. 1 or by the sensing elements of FIG. 1A;

FIG. 3 is a block diagram showing a magnetic field sensor including theCVH sensing element of FIG. 1 and having a combining circuit and a b_(n)control signal generator;

FIG. 4 is block diagram showing an exemplary combining circuit that canbe used as the combining circuit of FIG. 3, which includes switchingcircuits and a summing circuit;

FIG. 5 is a series of graphs showing behavior of exemplary b_(n) controlsignals generated by the b_(n) control signal generator of FIG. 3;

FIG. 6 is a block diagram of an exemplary b_(n) control signalgeneration circuit that can be used as the b_(n) control signalgenerator of FIG. 3;

FIG. 6A is a series of graphs showing behavior of b_(n) control signalsgenerated by the b_(n) control signal generator of FIG. 6;

FIG. 7 is a block diagram showing at least an exemplary combiningcircuit that can be used as the combining circuit of FIG. 3;

FIG. 8 is a graph showing an exemplary output signal from the switchingcircuits of FIG. 4 for particular b_(n) control signals;

FIG. 8A is a graph showing another exemplary output signal from theswitching circuits of FIG. 4 for different b_(n) control signals;

FIG. 9 is a graph showing an exemplary output signal from the combiningcircuit of FIG. 3; and

FIG. 10 is a block diagram showing a side view of a part of a CVHsensing element, which can be used to provide continuous output signalsfrom a plurality of vertical Hall elements, either with or withoutchopping.

DETAILED DESCRIPTION OF THE INVENTION

Before describing the present invention, some introductory concepts andterminology are explained. As used herein, the term “sensing element” isused to describe a variety of types of electronic elements that cansense a characteristic of the environment. For example, sensing elementsinclude, but are not limited to, pressure sensing elements, temperaturesensing elements, light sensing elements, acoustic sensing elements, andmagnetic field sensing elements.

As used herein, the term “sensor assembly” is used to describe a circuitor assembly that includes a sensing element and other components. Inparticular, as used herein, the term “magnetic field sensor assembly” isused to describe a circuit or assembly that includes a magnetic fieldsensing element and electronics coupled to the magnetic field sensingelement.

As used herein, the term “sensor” is used to describe either a sensingelement or a sensor assembly.

As used herein, the term “magnetic field sensing element” is used todescribe a variety of electronic elements that can sense a magneticfield. The magnetic field sensing elements can be, but are not limitedto, Hall effect elements, magnetoresistance elements, ormagnetotransistors. As is known, there are different types of Halleffect elements, for example, a planar Hall element, a vertical Hallelement, and a circular Hall element. As is also known, there aredifferent types of magnetoresistance elements, for example, a giantmagnetoresistance (GMR) element, an anisotropic magnetoresistanceelement (AMR), a tunneling magnetoresistance (TMR) element, an Indiumantimonide (InSb) sensor, and a magnetic tunnel junction (MTJ).

As is known, some of the above-described magnetic field sensing elementstend to have an axis of maximum sensitivity parallel to a substrate thatsupports the magnetic field sensing element, and others of theabove-described magnetic field sensing elements tend to have an axis ofmaximum sensitivity perpendicular to a substrate that supports themagnetic field sensing element. In particular, planar Hall elements tendto have axes of sensitivity perpendicular to a substrate, whilemagnetoresistance elements and vertical Hall elements (includingcircular vertical Hall (CVH) sensing elements) tend to have axes ofsensitivity parallel to a substrate.

Magnetic field sensors are used in a variety of applications, including,but not limited to, an angle sensor that senses an angle of a directionof a magnetic field, a current sensor that senses a magnetic fieldgenerated by a current carried by a current-carrying conductor, amagnetic switch that senses the proximity of a ferromagnetic object, arotation detector that senses passing ferromagnetic articles, forexample, magnetic domains of a ring magnet, and a magnetic field sensorthat senses a magnetic field density of a magnetic field.

While a circular vertical Hall (CVH) magnetic field sensing element,which has a plurality of vertical Hall magnetic field sensing elements,is described in examples below, it should be appreciated that the sameor similar techniques and circuits apply to any type of sensing elementsor any type of sensor assemblies, i.e., to any type of sensors.

Referring to FIG. 1, a circular vertical Hall (CVH) sensing element 12includes a circular implant region 18 having a plurality of verticalHall elements disposed thereon, of which a vertical Hall element 12 a isbut one example. Each vertical Hall element has a plurality of Hallelement contacts (e.g., four or five contacts), of which a vertical Hallelement contact 12 a is but one example.

A particular vertical Hall element (e.g., 12 a) within the CVH sensingelement 12, which, for example, can have five adjacent contacts, canshare some, for example, four, of the five contacts with a next verticalHall element (e.g., 12 b). Thus, a next vertical Hall element can beshifted by one contact from a prior vertical Hall element. For suchshifts by one contact, it will be understood that the number of verticalHall elements is equal to the number of vertical Hall element contacts,e.g., 32. However, it will also be understood that a next vertical Hallelement can be shifted by more than one contact from the prior verticalHall element, in which case, there are fewer vertical Hall elements thanthere are vertical Hall element contacts in the CVH sensing element.

A center of a vertical Hall element 0 is positioned along an x-axis 20and a center of vertical Hall element 8 is positioned along a y-axis 22.In the exemplary CVH 12, there are thirty-two vertical Hall elements andthirty-two vertical Hall element contacts. However, a CVH can have morethan or fewer than thirty-two vertical Hall elements and more than orfewer than thirty-two vertical Hall element contacts.

In some applications, a circular magnet 14 having a north side 14 a anda south side 14 b can be disposed over the CVH 12. The circular magnet14 tends to generate a magnetic field 16 having a direction from thenorth side 14 a to the south side 14 b, here shown to be pointed to adirection of about forty-five degrees relative to x-axis 20.

In some applications, the circular magnet 14 is mechanically coupled toa rotating object, for example, an automobile steering shaft or anautomobile camshaft, and is subject to rotation relative to the CVHsensing element 12. With this arrangement, the CVH sensing element 12 incombination with an electronic circuit described below can generate asignal related to the angle of rotation of the magnet 14.

Referring now to FIG. 1A, a plurality of sensing elements 30 a-30 h (oralternatively, sensors), in a general case, can be any type of sensingelements, including, but not limited to, pressure sensing elements,temperature sensing elements, light sensing elements, acoustic sensingelements, and magnetic field sensing elements. The magnetic fieldsensing elements 30 a-30 h can be, for example, planar Hall elements,vertical Hall elements, or magnetoresistance elements. These elementscan also be coupled to an electronic circuit, in particular, to acombining circuit described below. For embodiments where the sensingelements 30 a-30 h are vertical Hall elements, there can also be amagnet the same as or similar to the magnet 14 of FIG. 1, disposedproximate to the sensing elements 30 a-30 h.

While the sensing elements 30 a-30 h are shown to be arranged in acircle, in some embodiments, the sensing elements can be arranged inanother configuration, for example, in a line. Where the sensingelements 30 a-30 h are magnetic field sensing elements, such a lineararrangement can be used, for example, to detect a linear position of aferromagnetic object. Where the sensing elements 30 a-30 h are acousticsensors, such a linear arrangement can be used, for example, tocharacterize a position of a sound wave along a line.

Referring now to FIG. 2, a graph 50 has a horizontal axis with a scalein units of CVH vertical Hall element position, n, around a CVH sensingelement, for example, the CVH sensing element 12 of FIG. 1. The graph 50also has a vertical axis with a scale in amplitude in units ofmillivolts. The vertical axis is representative of output signal levelsfrom the plurality of vertical Hall elements of the CVH sensing element.

The graph 50 includes a signal 52 representative of output signal levelsfrom the plurality of vertical Hall elements of the CVH taken with themagnetic field of FIG. 1 pointing in a direction of forty-five degrees.

Referring briefly to FIG. 1, as described above, vertical Hall element 0is centered along the x-axis 20 and vertical Hall element 8 is centeredalong the y-axis 22. In the exemplary CVH sensing element 12, there arethirty-two vertical Hall element contacts and a corresponding thirty-twovertical Hall elements, each vertical Hall element having a plurality ofvertical Hall element contacts, for example, five contacts.

In FIG. 2, a maximum positive signal is achieved from a vertical Hallelement centered at position 4, which is aligned with the magnetic field16 of FIG. 1, such that a line drawn between the vertical Hall elementcontacts (e.g., five contacts) of the vertical Hall element at position4 is perpendicular to the magnetic field. A maximum negative signal isachieved from a vertical Hall element centered at position 20, which isalso aligned with the magnetic field 16 of FIG. 1, such that a linedrawn between the vertical Hall element contacts (e.g., five contacts)of the vertical Hall element at position 20 is also perpendicular to themagnetic field.

A sine wave 54 is provided to more clearly show the ideal behavior ofthe signal 52. The signal 52 has variations due to vertical Hall elementoffsets, which tend to somewhat randomly cause element output signals tobe too high or too low relative to the sine wave 54, in accordance withoffset errors for each element. The offset signal errors areundesirable.

Full operation of the CVH sensing element 12 of FIG. 1 and generation ofthe signal 52 of FIG. 2 are described in more detail in theabove-described PCT Patent Application No. PCT/EP2008056517, entitled“Magnetic Field Sensor for Measuring Direction of a Magnetic Field in aPlane,” filed May 28, 2008, which is published in the English languageas PCT Publication No. WO 2008/145662.

As will be understood from PCT Patent Application No. PCT/EP2008056517,groups of contacts of each vertical Hall element can be used in amultiplexed or chopped arrangement to generate chopped output signalsfrom each vertical Hall element. Thereafter, or in parallel (i.e., atthe same time), a new group of adjacent vertical Hall element contactscan be selected (i.e., a new vertical Hall element), which can be offsetby one element from the prior group. The new group can be used in themultiplexed or chopped arrangement to generate another chopped outputsignal from the next group, and so on.

Each step of the signal 52 can be representative of a chopped outputsignal from one respective group of vertical Hall element contacts,i.e., from one respective vertical Hall element. However, in otherembodiments, no chopping is performed and each step of the signal 52 isrepresentative of an unchopped output signal from one respective groupof vertical Hall element contacts, i.e., from one respective verticalHall element. Thus, the graph 52 is representative of a CVH outputsignal with or without the above-described grouping and chopping ofvertical Hall elements.

It will be understood that, using techniques described above in PCTPatent Application No. PCT/EP2008056517, a phase of the signal 52 (e.g.,a phase of the signal 54) can be found and can be used to identify thepointing direction of the magnetic field 16 of FIG. 1 relative to theCVH 12.

Referring now to FIG. 3, a circuit 70 includes a CVH sensing element 72having a plurality of vertical Hall elements, each vertical Hall elementcomprising a group of vertical Hall element contacts (e.g., fivevertical Hall element contacts), of which a vertical Hall elementcontact 73 is but one example.

In some embodiments, a switching circuit 74 can provide CVH outputsignals 72 a, also referred to as CVH output signals x_(n)=x₀ tox_(N-1), where n is equal to a vertical Hall element position (i.e., aposition of a group of vertical Hall element contacts that form avertical Hall element) in the CVH sensing element 72, and where thereare N such positions.

In some embodiments, the CVH output signals 72 a are comprised ofsequential output signals taken one-at-a-time around the CVH sensingelement 72, wherein each output signal is generated on a separate signalpath. In other embodiments, all of the CVH output signals 72 a aregenerated and provided continuously, wherein each one of the CVH outputsignals 72 a is still generated on a separate signal path. In the latterembodiments, the switching circuit 74 is not required. A continuousarrangement is described more fully below in conjunction with FIG. 10.

In one particular embodiment, the number of vertical Hall elements (eachcomprising a group of vertical Hall element contacts) in the CVH sensingelement 72 is equal to the total number of sensing element positions, N.In other words, the CVH output signals 72 a can be comprised ofsequential or parallel output signals, wherein each one of the CVHoutput signals 72 a is associated with a respective one of the verticalHall elements in the CVH sensing element 72, i.e., the circuit 10 stepsaround the vertical Hall elements of the CVH sensing element 72 byincrements of one, and N equals the number of vertical Hall elements inthe CVH sensing element 72. However, in other embodiments, theincrements can be by greater than one vertical Hall element, in whichcase N is less than the number of vertical Hall elements in the CVHsensing element 72.

In one particular embodiment, the CVH sensing element 72 has thirty-twovertical Hall elements, i.e., N=32, and each step is a step of onevertical Hall element contact position (i.e., one vertical Hall elementposition). In another embodiment, the CVH sensing element 72 hasthirty-two vertical Hall elements, i.e., N=32, and each step is a stepof two vertical Hall element contact positions (i.e., one vertical Hallelement position), which means that the CVH sensing element hassixty-four vertical Hall element contacts. In other embodiments, therecan be more than thirty-two or fewer than thirty-two vertical Hallelements in the CVH sensing element 72. Also, the increments of verticalHall element positions, n, can be greater than one vertical Hall elementcontact.

In general, a subscript is used herein is to represent a vertical Hallelement position, whether or not the number of vertical Hall elements isthe same as the number of element positions.

In some embodiments, another switching circuit 76 can provide theabove-described “chopping” of groups of the vertical Hall elementswithin the CVH sensing element 72.

Chopping will be understood to be an arrangement in which a group ofvertical Hall element contacts, for example, five vertical Hall elementcontacts are driven with current sources 86 in a plurality of connectionconfigurations, and signals are received from the group of vertical Hallelement contacts in corresponding configurations. Thus, in accordancewith each vertical Hall element position, n, there can be a plurality ofoutput signals during the chopping, and then the group increments to anew group, for example, by an increment of one vertical Hall elementcontact.

The circuit 70 includes an oscillator 78 that provides clock signals 78a, 78 b, 78 c, which can have the same or different frequencies. Adivider 80 is coupled to receive the clock signal 78 a and configured togenerate a clock signal 80 a. A switch control circuit 82 is coupled toreceive the clock signal 80 a and configured to generate switch controlsignals 82 a, which are received by the switching circuits 74, 76 tocontrol the sequencing around the CVH sensing element 72, and,optionally, to control chopping of groups of vertical Hall elementswithin the CVH sensing element 72 in ways described above.

The current sources 86 are used to bias the vertical Hall elements ofthe CVH sensing element 72 when operating with or without chopping.

A preprocessing circuit 88 is coupled to receive the CVH output signals72 a. In particular, a combining circuit 90 is coupled to receive theCVH output signals 72 a and configured to generate a preprocessed signal90 a.

The circuit 70 can include divider 108 coupled to receive the clocksignal 78 c and configured to generate a clock signal 108 a. A divider110 can be coupled to receive the clock signal 108 a and configured togenerate a clock signal 110 a.

The preprocessing circuit can include a b_(n)(k) control signalgenerator 92 coupled to receive the clock signal 108 a at a clock inputand coupled to receive the clock signal 110 a at a reset input.Operation of the b_(n)(k) control signal generator 92 is furtherdescribed below in conjunction with FIGS. 5, 6, and 6A. Let it sufficehere to say that the b_(n)(k) control signal generator 92 is configuredto generate control signals 92 a, b₀(k) to b_(N-1)(k), which are aplurality of control signals to control the combining circuit 90.

The combining circuit 90 is described more fully below in conjunctionwith FIG. 4. Let it suffice here to say that the combining circuit 90 isconfigured to combine the CVH output signals 72 a in ways that provideand enhanced performance of the circuit 70 that would otherwise not beavailable. The combining circuit 90 is configured to generate a combinedsignal 90 a, E(k).

Referring to the control signals 92 a, b₀(k) to b_(N-1)(k), as usedherein, an index variable (k) is used to describe an indexing of theb_(n)(k) control signals 92 a. As described above, the subscript n isused to represent a vertical Hall element position. For thirty-two suchvertical Hall elements (i.e., thirty-two groups of vertical Hall elementcontacts) in the CVH sensing element 72, there can be 32 such positions,and thus, there can be N=32 such control signals. The parameter k isused to describe a time indexing of the N control signals, such that atone time index value, the N control signals have a particular stateconfiguration, and at another time index value, the N control signalshave another particular state configuration. The b_(n)(k) controlsignals 92 a are described more fully below in conjunction with FIG. 5.

The circuit 70 can also include an x-y direction component circuit 94coupled to receive the combined signal 90 a and configured to generatean x-y angle signal 104 a representative of an angle of a magnetic fieldin a plane of the CVH sensing element. For example, the x-y angle signal104 a can be a digital signal representative of an angle of the magneticfield 16 of FIG. 1 relative to the CVH sensing element 12.

The x-y direction component circuit 94 can include an amplifier 96coupled to receive the combined signal 90 a and configured to generatean amplified signal 96 a. An optional band pass filter 98 can be coupledto receive the amplified signal 96 a and configured to generate afiltered signal 98 a.

A comparator 100 with hysteresis can be coupled to receive the filteredsignal 98 a and also coupled to receive a predetermined threshold signal106 and configured to generate a two-state signal 100 a. A counter 102can be coupled to receive the two-state signal 100 a at an enable input,to receive the clock signal 78 b at a clock input, and to receive theclock signal 110 a at a reset input.

The counter 102 is configured to generate a phase signal 102 a having acount representative of a phase between the two-state signal 100 a andthe clock signal 110 a. The phase signal is received by a latch 104 thatis latched in accordance with the clock signal 110 a. The latch 104 isconfigured to generate a latched signal 104 a.

It will become apparent that the latched signal 104 a is a multi-bitdigital signal that has a value representative of an angle of themagnetic field experience by the CVH sensing element 72.

In some embodiments, all parts of the circuit 70 are fabricated on asingle common substrate, for example, a silicon substrate.

Referring now to FIG. 4, a combining circuit 130 can be the same as orsimilar to the combining circuit 90 of FIG. 3. The combining circuit 130can include a plurality of switching circuits 136 a-136N, each coupledto receive a respective one of the CVH output signals 72 a, x_(n)=x₀ tox_(N-1), of FIG. 3. The switching circuits 136 a-136N are also eachcoupled to receive a respective one of the control signals 92 a, b₀(k)to b_(N-1)(k), of FIG. 3.

Optionally, respective sample and hold circuits 138 can be coupledbefore the switching circuits 136 a-136N. The sample and hold circuits138 can be used for embodiments described above in which the CVH outputsignals 72 a of FIG. 3 are sequentially generated. In these embodiments,sampled signals x′₀ to x′_(N-1), sampled sequentially and held, areprovided to the switching circuits 136 a-136N instead of the signals x₀to x_(N-1).

For embodiments also described above, for which the CVH output signals72 a of FIG. 3 are continuously generated, no sample and hold circuits138 are needed, and signals x₀ to x_(N-1) are provided at the same timeto the switching circuits 136 a-136N.

The switching circuits 136 a-136N generate respective switched signalsz₀(k) to z_(N-1)(k) (e.g., 32 switched signals). A summing circuit 134is coupled to receive the switched signals, z₀(k) to z_(N-1)(k), andconfigured to generate a combined signal 134 a, which can be the same asor similar to the combined signal 90 a of FIG. 3.

In operation, at any particular time, some of the control signals, b₀(k)to b_(N-1)(k), are in a high state and others are in a low state. Theswitching circuits 136 a-136N are responsive to respective states of thecontrol signals, b₀(k) to b_(N-1)(k), such that, in response to oneparticular state of a respective control signal, a respective one of theCVH output signals, x₀ to x_(N-1), is inverted as it passes through therespective switching circuit, and in response to the other differentstate of the control signal, the CVH output signal is not inverted.Outputs signals, z₀(k) to z_(N-1)(k), result, which can be differentialsignals as shown, or which, in other embodiments, can be signal-endedsignals.

It will be appreciated that the combined signal 134 a, E(k), isessentially a sum of signals, i.e., a sum of some of the CVH outputsignals, x₀ to x_(N-1), that are inverted along with some of the CVHoutput signals, x₀ to x_(N-1), that are not inverted.

In operation, the control signals, b₀(k) to b_(N-1)(k), change statefrom time to time. Changes of the control signals, b₀(k) to b_(N-1)(k),are more fully described below in conjunction with FIGS. 5, 8, and 8A.

Referring now to FIG. 5, graphs 152-158 each have a horizontal axis witha scale in units of vertical Hall element position around a CVH sensingelement, and a vertical axis having a scale in units representative of abinary state (1 (e.g., high) or 0 (e.g., low)) of the b_(n) controlsignals, b₀(k) to b_(N-1)(k) of FIG. 4 and the b_(n) control signals 92a of FIG. 3.

As described above, the Hall element positions, N positions, representedby the horizontal axes, can have steps of one vertical Hall element(i.e., one vertical Hall element contact) or steps of more than onevertical Hall element (i.e., more that one vertical Hall elementcontact). Furthermore, the positions can be indicative of positions ofrespective groups of Hall elements when used in a chopped arrangement.

Each one of the graphs represents the control signals, b₀(k) tob_(N-1)(k), taken at a different time. For example, the graph 152 showsthat, at a first time (or increment 0) of the indexing variable, k, thecontrol signals from b₀(0) to b_(N/2-1)(0) are low and the controlsignals from b_(N/2)(0) to b_(N-1)(0) are high.

As described above, the subscript index is representative of theposition, n, of the vertical Hall element (or group of vertical Hallelement contacts) around the CVH sensing element, and there are N suchpositions from 0 to N−1. The index, k, is representative of a timeincrement associated with a change of the control signals, b₀(k) tob_(N-1)(k).

At the 0^(th) increment of the index, k, the control signal b₀(0) is lowand is the control signal received by the switching circuit 136 a ofFIG. 4 at a particular time represented by k=0. The low control signal,b₀(0), can cause the switching circuit 136 a not to invert, resulting inz₀(0)=x₀(0). At the N/2 vertical Hall element position, the controlsignal, b_(N/2)(0), is high, causing a respective one of the switchingcircuits of FIG. 3 to invert, resulting in z_(N/2)(0)=−x_(N/2)(0). Atthe last vertical Hall element position, N−1, the respective controlsignal, b_(N-1)(0), is high, also causing the switching circuit 136N ofFIG. 3 to invert, resulting in z_(N-1)(0)=−x_(N-1)(0).

The graphs 154-158 are representative of one particular embodiment, forwhich, at each increment of the time index, k, the control signals b₀(k)to b_(N-1)(k) shift by one vertical Hall element position (i.e., by onevertical Hall element contact). Thus, referring to the graph 154, at the0^(th) increment of the index, k, the control signal b₀(1) is now highand is the control signal received by the switching circuit 136 a ofFIG. 4. The high control signal, b₀(1), can cause the switching circuit136 a to invert, resulting in z₀(1)=−x₀(1). At the N/2 vertical Hallelement position, the control signal, b_(N/2)(1), is now low, causing arespective one of the switching circuits of FIG. 3 not to invert,resulting in z_(N/2)(1)=x_(N/2)(1). At the last vertical Hall elementposition, N−1, the respective control signal, b_(N-1)(1), is still high,causing the switching circuit 136N of FIG. 3 to invert, resulting inz_(N-1)(1)=−x_(N-1)(1).

Similarly, referring to the graph 156, at the N/2 increment of theindex, k, the control signal b₀(N/2−1) is high and is the control signalreceived by the switching circuit 136 a of FIG. 4. The high controlsignal, b₀(N/2), can cause the switching circuit 136 a to invert,resulting in z₀(N/2)=−x₀(N/2). At the N/2 vertical Hall elementposition, the control signal, b_(N/2)(N/2), is low, causing a respectiveone of the switching circuits of FIG. 3 not to invert, resulting inz_(N/2)(N/2)=x_(N/2)(N/2). At the last vertical Hall element position,N−1, the respective control signal, b_(N-1)(N/2), is now low, causingthe switching circuit 136N of FIG. 3 not to invert, resulting inz_(N-1)(N/2)=x_(N-1)(N/2).

Finally, referring to the graph 158, at the N−1 increment of the index,k, the control signal b₀(N−1) is now low, causing the switching circuit136 a to not invert, resulting in z₀(N−1)=x₀(N−1). At the N/2 verticalHall element position, the control signal, b_(N/2)(N−1), is now high,causing a respective one of the switching circuits of FIG. 3 to invert,resulting in z_(N/2)(N−1)=−x_(N/2)(N−1). At the last vertical Hallelement position, N−1, the respective control signal, b_(N-1)(N−1), islow, causing the switching circuit 142 of FIG. 3 not to invert,resulting in z_(N-1)(N−1)=x_(N-1)(N−1).

While half of the control signals b₀(k) to b_(N/2-1)(k) at any incrementof the index, k, are shown to be high and the other half to be low, inother embodiments, other proportions of high and low control signals canbe used. This can include proportions all the way down to one controlsignal being in one state and all of the other control signals being inanother state. However, it will be understood from discussion below thata best signal to noise ratio is obtained when the proportion isone-half.

As used herein, the phrase “approximately half” refers to a range ofabout forty percent to about sixty percent.

Referring now to FIG. 6, a b_(n) control signal generator 170 can be thesame as or similar to the b_(n) control signal generator 92 of FIG. 3and can generate the b_(n) control signals of FIG. 5, which can be thesame as or similar to the b_(n) control signals 92 a of FIG. 3.

The b_(n) control signal generator 170 can include a first plurality offlip-flops 172-176 coupled to receive a clock signal 186 at respectiveclock inputs. The output from a prior flip-flop is coupled to a datainput of a next flip-flop. The plurality of flip-flops 172-176 iscoupled to receive a reset signal 184 at respective reset inputs.

A second plurality of flip-flops 178-182 is also coupled to receive theclock signal 186 at respective clock inputs. The output from a priorflip-flop is coupled to a data input of a next flip-flop. The pluralityof flip-flops 178-182 is coupled to receive the signal 184 at respectiveset inputs.

A last flip-flop 182 is coupled to provide its output signal to the datainput of the first flip-flop 172.

With the above arrangement, the flip-flops 172-176 are set low inaccordance with the reset signal 184, and the flip-flops 178-182 are sethigh.

The signal 186 can be the same as or similar to the clock signal 108 aof FIG. 3 and the signal 184 can be the same as or similar to the clocksignal 110 a of FIG. 3. With each subsequent rising edge of clock signal186, the position of the N/2 adjacent low signals and N/2 adjacent highsignals are shifted one position to the right.

Referring now to FIG. 6A, a chart 200 includes graphs 202-208, eachgraph showing the b_(n) control signals, b₀(k) to b_(N-1)(k). Each cycleof the clock signal 186 of FIG. 6 provides a new set of b_(n) controlsignals, b₀(k) to b_(N-1)(k), i.e., a new index value for the index, k.

Graphs 202-208 are very much like graphs shown and described above inconjunction with FIG. 5, and thus, the graphs 202-208 are not discussedfurther.

Referring now to FIG. 7, an exemplary circuit 220 can include circuitportions 221 a-221N, which is a circuit portion replicated N times,where N is the number of vertical Hall element positions, for examplethirty-two, in a CVH sensing element.

The circuit 220 can include a combining circuit, which can includeswitching circuits 234 a-234N and also a current summing circuit 242,which are coupled together. The combining circuit of FIG. 7 can be thesame as or similar to the combining circuits 90, 130 of FIGS. 3 and 4,respectively. The combining circuit of FIG. 7 can generate a combinedoutput signal 244, E(k), shown here as a differential signal. Thecombined output signal 244 can be the same as or similar to the combinedoutput signal 90 a of FIG. 3 and the combined output signal 134 a ofFIG. 4.

The circuit 220 can also include chopping modulators 230 a-230N (230b-230N not shown), which are coupled to receive the CVH output signals222, x₀ to x_(N-1), which can be the same as or similar to the CVHoutput signals x₀ to x_(N-1) of FIGS. 3 and 4. The chopping modulators230 a-230N are also coupled to provide bias signals 222 (e.g., currentsignals) and reference voltage connections 222 to the CVH sensingelement. Bias signals and reference connections are described more fullybelow in conjunction with FIG. 10.

As described above, chopping uses a group of Hall element contacts, forexample, five contacts, here within a CVH sensing element, and switchesin various ways between the elements of the group. Thereafter, thechopping moves to a next element position, i.e., indexes around the CVHsensing element by an index step, for example, by one vertical Hallelement contact within the CVH sensing element, where chopping is againperformed on a next vertical Hall element.

As described above, in some embodiments, the chopping is not performedand the chopping modulators 230 a-230N are not used.

Differential pairs 232 a-232N (232 b-232N not shown) are coupled toreceive output signals from the chopping modulators 230 a-230N,respectively. The differential pairs 232 a-232N can generate currentsignals that are received by the switching circuits 234 a-234N,respectively. Conversion from voltage signals to current signals allowsfor simple summation of signals 242 from the plurality of switchingcircuits 234 a-234N to generate the combined output signal 244.

The switching circuits 234 a-234N are coupled to receive control signals224, b₀(k) to b_(N-1)(k), respectively, as described above inconjunction with FIG. 4. It will be understood from discussion abovethat the switching circuits 234 a-234N are configured to either invertor to not invert current signals provided by the differential pairs 232a-232N, depending upon states of the control signals 224.

The chopping modulators 230 a-230N are coupled to receive a Hall elementchopping clock 228, which can be the same clock for each one of thechopping modulators 230 a-230N, either sequentially or in parallel.

The chopping modulators 230 a-230N can also be coupled to receive two ormore Hall element bias signals 240 used in the chopping process. TheHall element bias signals can be the same for each one of the choppingmodulators 230 a-230N, either sequentially or in parallel.

The differential pairs 232 a-232N can be coupled to receive differentialpair bias signals 226. The differential pair bias signals 226 can be thesame for each one of the differential pairs 232 a-232N, eithersequentially or in parallel.

Referring now to FIG. 8, a graph 250 includes a horizontal axis with ascale in units of CVH element position, n. The graph 250 also includes avertical axis with units of magnitude in millivolts. The vertical scaleis representative of magnitude of switched element signals z₀(k) toz_(N-1)(k) (see, e.g., FIG. 4) for a k index value of four. While shownin voltage units in millivolts, the magnitude can either be in units ofvoltage or in units of current, depending upon the type of circuitsused. The k index value of four is representative of a particular shiftof the b_(n) control signals (see, e.g., FIG. 5).

For reference only, a sine wave 254 is shown, which is like the sinewave 54 of FIG. 2.

A signal 256 is representative of the switched element signals (e.g.,z₀(4) to z_(N-1)(4)) from each one of thirty-two vertical Hall elementpositions within the CVH sensing element, before the signals arecombined, for example, by the summing circuit 134 of FIG. 4. Comparingthe signal 254 to the signal 52 of FIG. 2, it will be understood thatfrom CVH element position 4 to CVH element position 19, the signal 256is identical to the signal 52, while from CVH element positions 20 to 31and positions 0 to 3, the signal 256 is inverted from the signal 52.Transitions 256 a and 256 b are apparent.

It will be apparent that if all of the magnitudes (steps) of the signal256 were summed, e.g., by the summing circuit 134 of FIG. 4, the sumwould be near zero.

Referring now to FIG. 8A, a graph 270 includes a horizontal axis with ascale in units of CVH element position, n. The graph 270 also includes avertical axis with units of magnitude in millivolts. The vertical scaleis representative of magnitude of switched element signals z₀(k) toz_(N-1)(k) (see, e.g., FIG. 4) for a k index value of twenty-eight. Thek index value of twenty-eight is representative of another particularshift of the b_(n) control signals (see, e.g., FIG. 5).

For reference only, a sine wave 274 is shown, which is like the sinewave 54 of FIG. 2.

A signal 272 is representative of the switched element signals (e.g.,z₀(28) to z_(N-1)(28)) from each one of thirty-two vertical Hall elementpositions within the CVH sensing element, before the signals arecombined, for example, by the summing circuit 134 of FIG. 4. Comparingthe signal 272 to the signal 52 of FIG. 2, it will be understood thatfrom CVH element position 28 to CVH element position 31 and frompositions 0 to 11, the signal 272 is identical to the signal 52, whilefrom element positions 12 to 27, the signal 256 is inverted from thesignal 52.

It will be apparent that if all of the magnitudes (steps) of the signal272 were summed, e.g., by the summing circuit 134 of FIG. 4, the sumwould be near to a maximum.

Referring now to FIG. 9, a graph 300 includes a horizontal axis in unitsof the index value k. The graph 300 also includes a vertical scale inunits of voltage in millivolts. A signal 302 is representative of asummed signal, for example, the summed signal 90 a of FIG. 3 or thesummed signal 134 a of FIG. 4, for all N possible shifts of the b(n)control signals.

For reference only, a sine wave 304 is shown.

Comparing the signal 302 with the signals 256, 272 of FIGS. 8 and 8A, itcan be seen that the signal 302 is near zero when the index value, k, isequal to four, and the signal 302 is near to a maximum when the indexvalue, k, is equal to twenty-eight.

It will be noted that the offset errors in the signals 52, 256, 276 ofFIGS. 3, 8, and 8A, which cause voltage deviations from the ideal sinewave from element position to element position, are greatly reduced inthe signal 302 of FIG. 9. This is due to the summing provided by thesumming circuit 134 of FIG. 4, which tends to average any random offsetsignals.

Referring briefly to FIG. 2, as described above, the pointing directionof the magnetic field 16 of FIG. 1, forty-five degrees, can bedetermined according to a maximum of the signal 52 at the CVH elementposition of four.

Referring again to FIG. 9, the pointing direction of the magnetic field16 of FIG. 1 can instead be determined according to a zero crossing ofthe signal 302 at the index value, k, of four. Note that there are twozero crossings, one near k=4 and one near k=20. The zero crossing withthe negative slope, from positive E(k) to negative E(k), will correspondto the pointing direction of the magnetic field. However, the signal 302has less random fluctuation than the signal 52, and thus, the anglemeasurement should be more accurate.

The magnitude of the signal 302 is shown to be larger than the magnitudeof the signal 52 of FIG. 2. The larger magnitude of the signal 302 isexpected due to the summation of signals by the summing circuits, forexample, by the summing circuit 134 of FIG. 4. The signal 302 can berepresented as:

${E\left( {\theta_{IN},k} \right)} = {\frac{2\;{GN}}{\pi}{\cos\left\lbrack {\theta_{IN} + {\frac{2\pi}{N}\left( {k - \frac{1}{2}} \right)}} \right\rbrack}}$

-   -   where:    -   θ_(IN)=magnetic field angle in plane of CVH sensing element;    -   k=b_(n) control signal index;    -   N=total number of vertical Hall element positions used in the        CVH sensing element; and    -   G=a constant related to maximum CVH sensor signal output, e.g.,        an amplitude of the sine wave signal 54 (FIG. 2) or an        approximate amplitude of the signal 52 (FIG. 2), for example:        G=BSg _(m) R _(out)        -   where:        -   B=magnetic field magnitude (Gauss);        -   S=vertical Hall element sensitivity (volts/Gauss);        -   g_(m)=transconductance of differential pair 232 a of FIG. 5;        -   Rout=transresistance of an output amplifier (volts/amps)            (e.g., 236 of FIG. 7)            Thus, the magnitude of the result at any angle is:            2GN/π,            which is directly proportional the number of sensing            elements in the summation. Using the signal of FIG. 2, which            has a zero-to-peak amplitude of 5 mV, 2GN/pi becomes 2*(5            mV)*32/pi=102 mV, which is consistent with the amplitude of            the signal 302 (or 304) of FIG. 9.

It will be appreciated that the higher amplitude of the signal 304results in an improved signal to noise ratio.

It will be appreciated from the above equation that when θ_(IN)=45° orπ/4, k=4.5 gives E(θ_(IN),k)=0, thus the exact location for the zerocrossing of E(θ_(IN),k) will be between positions 4 and 5. It will alsobe appreciated from the above equation that when θ_(IN)=45° orπ/4,k=28.5 gives E(θ_(IN),k)=2GN/π, or the maximum of E(θ_(IN),k), thusthe exact location for the maximum of E(θ_(IN),k) will be betweenpositions 28 and 29. Also note that any angle can be determined from thevalue of k that results in the first zero crossing of E(θ_(IN),k), whichis when the argument of the cosine function is π/2 or 90°. This isdetermined from the equation:

$\theta_{IN} = {{+ \frac{\pi}{2}} - {\frac{2\pi}{N}\left( {k - \frac{1}{2}} \right)}}$

As described in FIG. 3, the signal 302 (the signal 90 a of FIG. 3) canbe subsequently processed by the x-y direction component circuit 94 toidentify a phase of the signal 90 a, which is representative of theangle of the magnetic field. The signal 104 a of FIG. 3 provides thephase representative of magnetic input angle.

While the circuits and methods described herein are shown by example ofvertical Hall elements within a CVH sensing element, as described above,it should be appreciated that the same techniques can be used to processsignals from a plurality of any type of sensing element. In someembodiments, the circuits and methods can be used to identify a largestsignal from among the plurality of sensing elements. The same benefitsof reduced offset signal variations and increased amplitude andprocessing speed will apply to any type of sensing elements, and notonly to magnetic field sensing elements. For example, the sametechniques could be applied to a plurality of acoustic sensing elementsused to sense an acoustic signal. Depending upon the type of sensingelements, the x-y direction component circuit 94 of FIG. 3 may or maynot be applicable. Other types of processing of the summed signal 90 aof FIG. 3 may or may not be provided.

It should also be apparent that the same benefits can be achieved inrelation to any type of sensor assemblies, i.e., to any type of sensors.For example, the same techniques could be applied to a plurality ofmagnetic field sensors, each having a magnetic field sensing element andassociated processing circuitry, wherein the processing described hereincan be applied to output signals from the magnetic field sensorsdownstream from the magnetic field sensing elements, e.g., to outputsignals from the magnetic field sensors.

As described above in conjunction with FIG. 4, the CVH sensing elementdescribed herein can be used either in a mode that provides sequentialoutput signals from a plurality of vertical Hall elements or in a modethat can provide simultaneous and continuous output signals from aplurality of vertical Hall elements. A sequential arrangement isdescribed in PCT Patent Application No. PCT/EP2008056517, which isincorporated by reference above. A continuous arrangement is describedmore fully below in conjunction with FIG. 10.

Referring now to FIG. 10, a portion of a CVH sensing element 320 isshown in panels A-D in four side views having a respective fourdifferent exemplary drive and signal arrangements. The drive and signalarrangements can be switched, for example, by the switching circuit 76of FIG. 3., so that the arrangements of panels A-D are achievedsequentially in the above-described chopping of vertical Hall elements.However, if there is no chopping, the arrangement of any one of thepanels A-D can be retained continuously.

The panels A-D have the same reference designations to indicate the sameelements. The CVH sensing element 320 includes a plurality of verticalHall element contacts, of which vertical Hall element contacts 322 a-322m are but some of the vertical Hall element contacts in the CVH sensingelement 320. The vertical Hall element contacts 322 a-322 m are arrangedover a section of a common circular implant region 324 in a substrate(not shown), which can be the same as or similar to the common circularimplant region 18 of FIG. 1. The vertical Hall element contacts 322a-322 m can be the same as or similar to the vertical Hall elementcontacts (i.e., 12 aa) of FIG. 1.

Vertical hall elements 322 a-322 m are arranged with groups of fivevertical Hall element contacts, each group representing a vertical Hallelement. For example, referring to panel A of FIG. 10, a first verticalHall element 327 aa includes the vertical Hall element contacts 322b-322 f. A second vertical Hall element 327 ab includes the verticalHall element contacts 322 d-322 h. A third vertical 327 ac includes thevertical Hall element contacts 322 f-322 j.

Still referring to panel A of FIG. 10, for the first vertical Hallelement 327 aa, current sources 326, 328 drive currents into thevertical Hall element contacts 322 b, 322 f. A reference coupling 334 isused to couple the vertical Hall element contact 322 d to a referencevoltage, for example, a ground voltage. Current from the current source326 passes through the vertical Hall element contact 322 b and splits intwo, with approximately half of the current flowing toward the referencecoupling 334 and approximately half of the current flowing towardanother reference coupling (not shown) connected to a vertical Hallelement contact positioned to the left of vertical Hall element contact322 b. Similarly, the current from the current source 328 passes throughvertical Hall element contact 322 f and splits in two, withapproximately half of the current flowing toward the reference coupling334 and approximately half of the current flowing toward the referencecoupling 336. Thus, for the first vertical Hall element 327 aa, currentsflow from the vertical Hall element contacts 322 b, 322 f to thevertical Hall element contact 322 d as indicated by arrows and dashedlines.

Still referring to the first vertical Hall element 327 aa in panel A ofFIG. 10, if a positive magnetic field is present in a directionperpendicular to the first vertical Hall element 327 aa and facing intothe page, the upward-flowing current under vertical Hall element contact322 d creates a positive voltage when measured from vertical Hallelement contact 322 c to vertical Hall element contact 322 e, accordingto the Hall effect. Therefore an output voltage, V_(1a), of the firstvertical Hall element 327 aa is oriented so that the positive terminalis on the left, connected to the vertical Hall element contact 322 c,and the negative terminal is on the right, connected to the verticalHall element contact 322 e.

For the second vertical Hall element 327 ba, the current source 328drives a current into the vertical Hall element contact 322 f. Referencecouplings 334, 336 are used to couple the vertical Hall element contacts322 d, 322 h to a reference voltage, for example, a ground voltage. Asdescribed above, the current from the current source 328 passes throughvertical Hall element contact 322 f and splits in two, withapproximately half of the current flowing toward reference coupling 336and approximately half of the current flowing toward reference coupling334. Thus, the current source 328 and the reference coupling 334 arecontinuously shared between the first and second vertical Hall elements327 aa,327 ba, respectively. For the second vertical Hall element 327ba, currents flow from the vertical Hall element contact 322 f to thevertical Hall element contacts 322 d, 322 h as indicated by arrows anddashed lines.

Still referring to the second vertical Hall element 327 ba in panel A ofFIG. 10, if a positive magnetic field is present in a directionperpendicular to the second vertical Hall element 327 ba and facing intothe page, the downward-flowing current under vertical Hall elementcontact 322 f creates a positive voltage when measured from the verticalHall element contact 322 g to the vertical Hall element contact 322 e,according to the Hall effect. Therefore an output voltage, V_(2a), ofthe second vertical Hall element 327 ba is oriented so that the positiveterminal is on the right, connected to the vertical Hall element contact322 g, and the negative terminal is on the left, connected to thevertical Hall element contact 322 e. Note also that the negativeterminal connection connected to the vertical Hall element contact 322 eis continuously shared between the first and second vertical Hallelements 327 aa,327 ba, respectively.

For the third vertical Hall element 327 ca, current sources 328, 330drive currents into the vertical Hall element contacts 322 f, 322 j. Areference coupling 336 is used to couple the vertical Hall elementcontact 322 h to a reference voltage, for example, a ground voltage.Thus, currents flow from the vertical Hall element contacts 322 f, 322 jto the vertical Hall element contact 322 h as indicated by arrows anddashed lines. As described above, the current from the current source328 passes through the vertical Hall element contact 322 f and splits intwo, with approximately half of the current flowing toward the referencecoupling 334 and approximately half of the current flowing toward thereference coupling 336. Similarly, the current from the current source330 passes through vertical Hall element contact 322 j and splits intwo, with approximately half of the current flowing toward the referencecoupling 336 and approximately half of the current flowing toward thereference coupling 338. Thus, for the third vertical Hall element 327ca, currents flow from the vertical Hall element contacts 322 f, 322 jto the vertical Hall element contact 322 h as indicated by arrows anddashed lines.

Still referring to the third vertical Hall element 327 ca in panel A ofFIG. 10, if a positive magnetic field is present in a directionperpendicular to the third vertical Hall element 327 ca and facing intothe page, the upward-flowing current under vertical Hall element contact322 h creates a positive voltage when measured from the vertical Hallelement contact 322 g to the vertical Hall element contact 322 i,according to the Hall effect. Therefore an output voltage, V_(3a), ofthe third vertical Hall element 327 ca is oriented so that the positiveterminal is on the left, connected to vertical Hall element contact 322g, and the negative terminal is on the right, connected to vertical Hallelement contact 322 i.

Other vertical Hall elements in the CVH sensing element 320 aresimilarly coupled. Although not depicted in panel A of FIG. 10, allvertical Hall element contacts in panel A are circularly arranged over acommon circular implant region so that additional vertical Hall elementcontacts to the right of vertical Hall element contact 322 m will adjoinnext to additional vertical Hall element contacts to the left ofvertical Hall element contact 322 a. With this arrangement, adjacentcouplings are identical for all elements, including elements that definestarting and ending points around the circular CVH structure.

It will be understood that the arrangement of panel A can be maintainedcontinuously, in which case, the number of vertical Hall elements isequal to half of the total number of vertical Hall element contacts. Forexample, if there are sixty-four vertical Hall element contacts in theCVH sensing element 320, then there are thirty-two vertical Hallelements, each providing a continuous output signal.

If the arrangement of panel A is maintained, then a plurality of outputsignals from the CVH sensing element 320 are continuous signals, inwhich case, the sample and hold circuits 138 of FIG. 4 are not neededand continuous signals (i.e., x₀-x_(N-1)) can be presented to theswitching circuits 136 a-136N of FIG. 4. The same is true if any of thearrangements of panels B-D are continuously maintained.

While panel A is representative of vertical Hall elements using all ofthe vertical Hall element contacts in the CVH sensing element, in someembodiments, only two or more vertical Hall elements provide outputsignals at the same time, wherein the two vertical Hall elements caneither share vertical Hall element contacts or not. Each vertical Hallelement can generate a differential output signal.

It should be understood that the current sources 326, 328, 330 and thereference couplings 334, 328, 330 represent particular drive signalgenerators to drive the vertical Hall elements 327 ab, 327 bb, 327 cb inorder to generate output signals. However, it should be recognized thatthere are other drive arrangements, for example, using voltage sources.

Panels B-D are representative of a chopping arrangement in which alloutput signals are still available, but for which each output signal(i.e., each vertical Hall element) is chopped to provide four outputsignal versions. Current directions in relation to output voltagepolarities in panels B-D will be understood from discussion above inconjunction with panel A.

Referring now to panel B, the current sources 326, 328, 330 are shiftedto the right by one vertical Hall element contact. The referencecouplings 334, 336, 338 are also shifted to the right by one and anadditional reference coupling 340 is shown coupled to the vertical Hallelement contact 322 a.

In panel B, the first, second, and third vertical Hall elements 327 ab,327 bb, 327 cb are shifted to the right from their previous positions byone vertical Hall element contact. An output voltage signals V_(1b) fromthe first vertical Hall element 327 ab results between the vertical Hallelement contacts 322 d, 322 f. An output voltage signals V_(2b) from thesecond vertical Hall element 327 bb results between the vertical Hallelement contacts 322 f, 322 h. An output voltage signals V_(3b) from thethird vertical Hall element 327 cb results between the vertical Hallelement contacts 322 h, 322 j.

Referring now to panel C, the current sources 326, 328, 330 are againshifted to the right by one vertical Hall element contact. The referencecouplings 334, 336, 338, 340 are also shifted to the right by one.

In panel C, the first, second, and third vertical Hall elements 327 ac,327 bc, 327 cc are shifted to the left from their previous positions byone vertical Hall element contact. An output voltage signals V_(1c) fromthe first vertical Hall element 327 ac results between the vertical Hallelement contacts 322 c, 322 e. An output voltage signals V_(2c) from thesecond vertical Hall element 327 bc results between the vertical Hallelement contacts 322 e, 322 g. An output voltage signals V_(3c) from thethird vertical Hall element 327 cc results between the vertical Hallelement contacts 322 g, 322 i.

Referring now to panel D, the current sources 326, 328, 330 are againshifted to the right by one vertical Hall element contact. The referencecouplings 334, 336, 338, 340 are also shifted to the right by one. Anadditional current source 332 is shown coupled to the vertical Hallelement contact 322 a.

In panel D, the first, second, and third vertical Hall elements 327 ad,327 bd, 327 cd are shifted to the right from their previous positions byone vertical Hall element contact. An output voltage signals V_(1d) fromthe first vertical Hall element 327 ad results between the vertical Hallelement contacts 322 d, 322 f. An output voltage signals V_(2d) from thesecond vertical Hall element 327 bd results between the vertical Hallelement contacts 322 f, 322 h. An output voltage signals V_(3d) from thethird vertical Hall element 327 cd results between the vertical Hallelement contacts 322 h, 322 j.

While the first, second, and third vertical Hall elements are shown toshift right and left in the panels A-D, for the purposes of chopping,they can still considered to be the same vertical Hall element. It willbe recognized that by shifting right and left, in the presence of astatic magnetic field, the vertical Hall elements will output slightlydifferent signal magnitudes and phases upon each shift. However, unlikethe offset voltages represented by the irregular steps of the signal 52of FIG. 2, the magnitude and phase shifts caused by the shiftingpositions are deterministic and can be removed by subsequent processingif desired.

For chopping, taking the first vertical Hall element 327 aa, 327 ab, 327ac, 327 ad as an example, with the four possible couplings of the driveand reference contacts (current in, current out, positive voltagemeasurement, negative voltage measurement), any offset voltagesassociated with the first vertical Hall element, when combined using anaverage of the output voltage signals V_(1a), V_(1b), V_(1c), V_(1d),will nearly cancel. Thus, chopping can achieve a reduction in the offsetvoltages otherwise represented in the signal 52 of FIG. 2.

It will also be recognized that the combining circuit 90 of FIG. 3combines a plurality of signals from a plurality of vertical Hallelements. Thus, the combining circuit 90 also tends to reduce the effectof offset voltages, resulting in a signal 302 (FIG. 9) having regularrather than random steps.

Therefore, in some embodiments of the circuit 70 of FIG. 3 no choppingis used and in other embodiments, chopping is used. Also, in someembodiments, only a subset of the arrangements of panels A-D are used,for example, only the arrangements of panel A and panel B are used.

In some embodiments the chopping, i.e., the switching between thearrangements of panels A-D occurs with a chopping rate in the range ofabout 100 kHz to about 10 MHz.

While the vertical Hall elements of FIG. 10 are represented as groups offive vertical Hall element contacts, in some embodiments, there can bemore than five vertical Hall element contacts in each vertical Hallelement. In still other embodiments, there can be three or four verticalHall element contacts in each vertical Hall element.

While the continuously driven vertical Hall elements are shown tooverlap by three vertical Hall element contacts (i.e., they share threevertical Hall element contacts), in other embodiments, the continuouslydriven vertical Hall elements can overlap by one vertical Hall elementcontact. (see, e.g., vertical Hall elements 327 aa, 327 ca).

In still other embodiment, circumferential centers (in a directionaround the circle of the CVH sensing element) of two continuously drivenvertical Hall elements are angularly disposed around the CVH sensingelements by less than one hundred eighty degrees. Thus, in theseembodiments, the two vertical Hall elements generate output signals thatare not representative of opposite magnetic field directions relative toeach other.

In some embodiments, circumferential centers of the continuously drivenvertical Hall elements are angularly disposed around the CVH sensingelements by an angle less than or equal to about forty-five degrees.

It should be understood that a configuration, such as that of FIG. 10,for which the plurality of output signals are generated continuouslyrather than sequentially by the CVH sensing element, will tend to resultin a faster angle sensor that is more quickly responsive to any changein a direction of a magnetic field.

It will also be understood that, where chopping is used, a fasterchopping (e.g., between the arrangements of panels A-D) will tend toresult in a faster angle sensor that is more quickly responsive to anychange in a direction of a magnetic field. An even faster angle sensormay be achieved with no chopping, in which case the combining circuit 90of FIG. 4 can provide, among other benefits, the reduction of offsetvoltages.

While an example of a CVH sensing element used in a way to providecontinuous output signals is shown above, as described further above, inother embodiments, the CVH sensing element can instead be used in a wayto provide sequential output signals. For those embodiments, thesequencing and chopping is more straightforward. For example, a firstvertical Hall element can first be selected having, for example, fivevertical Hall element contacts, and can provide an output signal. Ifchopping is desired, the configuration of the bias signal, referencecoupling, and output signals of the first selected vertical Hall elementcan be reconfigured, for example, to provide multiple output signalsthat can be averaged. Thereafter, a next vertical Hall element can beselected, which can be offset from the first selected vertical Hallelement, for example, by one vertical Hall element contact from thefirst selected vertical Hall element, and the chopping can be repeated.If no chopping is used, a particular single configuration of bias,reference, and output signals from each selected vertical Hall elementcan be used.

While a CVH sensing element is used in examples of an angle sensorabove, it should be understood that the same benefits can be achievedwith another type of angle sensor, for example, a plurality of separatevertical Hall elements or a plurality of separate magnetoresistanceelements.

All references cited herein are hereby incorporated herein by referencein their entirety.

Having described preferred embodiments, which serve to illustratevarious concepts, structures and techniques, which are the subject ofthis patent, it will now become apparent to those of ordinary skill inthe art that other embodiments incorporating these concepts, structuresand techniques may be used. Accordingly, it is submitted that that scopeof the patent should not be limited to the described embodiments butrather should be limited only by the spirit and scope of the followingclaims.

What is claimed is:
 1. A method of operating a circular vertical Hall(CVH) sensing element having a plurality of vertical Hall elementcontacts disposed in a circle over a common implant region in asubstrate, the method comprising: selecting a plurality of groups ofvertical Hall element contacts from among the plurality of vertical Hallelement contacts, each group representative of a respective one of aplurality of vertical Hall elements, wherein the selecting comprisesselecting a first group of vertical Hall element contacts representativeof a first vertical Hall element, and selecting a second group ofvertical Hall element contacts representative of a second vertical Hallelement; and driving at the same time the first and the second verticalHall elements to provide at the same time a first vertical Hall elementoutput signal between two of the vertical Hall element contacts of thefirst group and a second vertical Hall element output signal between twoof the vertical Hall element contacts of the second group, wherein theselecting further comprises: selecting a third group of vertical Hallelement contacts representative of a third vertical Hall element fromamong the plurality of vertical Hall element contacts, and wherein thedriving further comprises: driving at the same time the third verticalHall element to provide at the same time a third vertical Hall elementoutput signal between two of the vertical Hall element contacts of thethird group.
 2. The method of claim 1, wherein the first and the secondgroups of vertical Hall element contacts share at least one verticalHall element contact with each other.
 3. The method of claim 1, whereinthe first and the second groups of vertical Hall element contacts shareat least three vertical Hall element contacts with each other.
 4. Themethod of claim 1, wherein circumferential centers of the first and thesecond vertical Hall elements are disposed at positions around the ringseparated by less than one hundred eighty degrees.
 5. The method ofclaim 1, wherein the plurality of groups of vertical Hall elementcontacts and associated vertical Hall elements comprise all of theplurality of vertical Hall element contacts in the circular verticalHall sensing element used in a vertical Hall element, wherein the methodfurther comprises: driving at the same time each one of the verticalHall elements to provide at the same time vertical Hall element outputsignals between two respective vertical Hall element contacts of eachone of the vertical Hall elements.
 6. The method of claim 1, furthercomprising: at a chopping rate, changing the vertical Hall elementcontacts to which drive signal sources are coupled in each one of therepresented vertical Hall elements; and separately summing or separatelyaveraging the output signals from each one of the represented verticalHall elements as the changing occurs.
 7. A method of operating acircular vertical Hall (CVH) sensing element having a plurality ofvertical Hall element contacts disposed in a circle over a commonimplant region in a substrate, the method comprising: selecting aplurality of groups of vertical Hall element contacts from among theplurality of vertical Hall element contacts, each group representativeof a respective one of a plurality of vertical Hall elements, whereinthe selecting comprises selecting a first group of vertical Hall elementcontacts representative of a first vertical Hall element, and selectinga second group of vertical Hall element contacts representative of asecond vertical Hall element; and driving at the same time the first andthe second vertical Hall elements to provide at the same time a firstvertical Hall element output signal between two of the vertical Hallelement contacts of the first group and a second vertical Hall elementoutput signal between two of the vertical Hall element contacts of thesecond group, wherein the first and the second groups of vertical Hallelement contacts share at least one vertical Hall element contact witheach other.
 8. The method of claim 7, wherein the first and the secondgroups of vertical Hall element contacts share at least three verticalHall element contacts with each other.
 9. The method of claim 7, whereincircumferential centers of the first and the second vertical Hallelements are disposed at positions around the ring separated by lessthan one hundred eighty degrees.
 10. The method of claim 7, wherein theplurality of groups of vertical Hall element contacts and associatedvertical Hall elements comprise all of the plurality of vertical Hallelement contacts in the circular vertical Hall sensing element used in avertical Hall element, wherein the method further comprises: driving atthe same time each one of the vertical Hall elements to provide at thesame time vertical Hall element output signals between two respectivevertical Hall element contacts of each one of the vertical Hallelements.
 11. The method of claim 7, further comprising: at a choppingrate, changing the vertical Hall element contacts to which drive signalsources are coupled in each one of the represented vertical Hallelements; and separately summing or separately averaging the outputsignals from each one of the represented vertical Hall elements as thechanging occurs.
 12. A circular vertical Hall (CVH) sensing elementcircuit, comprising: a substrate; a common circular implant region in asurface of the substrate; a plurality of vertical Hall element contactsdisposed in a circle over the common implant region and upon thesurface, each group representative of a respective one of a plurality ofvertical Hall elements, a first group representative of a first verticalHall element, and a second group representative of a second verticalHall element; and respective first and second drive signal generatorsdisposed upon the substrate and configured to drive at the same time thefirst and the second vertical Hall elements to provide at the same timea first vertical Hall element output signal between two of the verticalHall element contacts of the first group and a second vertical Hallelement output signal between two of the vertical Hall element contactsof the second group, wherein a third group selected from the pluralityof vertical Hall element contacts is representative of a third verticalHall element, the circular vertical Hall (CVH) sensing element circuitfurther comprising a respective third drive signal generator disposedupon the substrate and configured to drive at the same time the thirdvertical Hall element to provide at the same time a third vertical Hallelement output signal between two of the vertical Hall element contactsof the third group.
 13. The circular vertical Hall (CVH) sensing elementcircuit of claim 12, wherein the first and the second groups of verticalHall element contacts share at least one vertical Hall element contactwith each other.
 14. The circular vertical Hall (CVH) sensing elementcircuit of claim 12, wherein the first and the second groups of verticalHall element contacts share at least three vertical Hall elementcontacts with each other.
 15. The circular vertical Hall (CVH) sensingelement circuit of claim 12, wherein the plurality of groups of verticalHall element contacts and associated plurality of vertical Hall elementscomprise all of the plurality of vertical Hall element contacts in thecircular vertical Hall sensing element, wherein the circular verticalHall (CVH) sensing element circuit further comprises: respective drivesignal sources disposed upon the substrate and configured to drive atthe same time each one of the vertical Hall elements to provide at thesame time vertical Hall element output signals between two respectivevertical Hall element contacts of each one of the vertical Hallelements.
 16. A circular vertical Hall (CVH) sensing element circuit,comprising: a substrate; a common circular implant region in a surfaceof the substrate; a plurality of vertical Hall element contacts disposedin a circle over the common implant region and upon the surface, eachgroup representative of a respective one of a plurality of vertical Hallelements, a first group representative of a first vertical Hall element,and a second group representative of a second vertical Hall element; andrespective first and second drive signal generators disposed upon thesubstrate and configured to drive at the same time the first and thesecond vertical Hall elements to provide at the same time a firstvertical Hall element output signal between two of the vertical Hallelement contacts of the first group and a second vertical Hall elementoutput signal between two of the vertical Hall element contacts of thesecond group, wherein the first and the second groups of vertical Hallelement contacts share at least one vertical Hall element contact witheach other.
 17. The circular vertical Hall (CVH) sensing element circuitof claim 16, wherein the first and the second groups of vertical Hallelement contacts share at least three vertical Hall element contactswith each other.
 18. The circular vertical Hall (CVH) sensing elementcircuit of claim 16, wherein the plurality of groups of vertical Hallelement contacts and associated plurality of vertical Hall elementscomprise all of the plurality of vertical Hall element contacts in thecircular vertical Hall sensing element, wherein the circular verticalHall (CVH) sensing element circuit further comprises: respective drivesignal sources disposed upon the substrate and configured to drive atthe same time each one of the vertical Hall elements to provide at thesame time vertical Hall element output signals between two respectivevertical Hall element contacts of each one of the vertical Hallelements.